Finding the sweet spot with sports nutrition

by Alan McCubbin

So often the mentality in nutrition (and particularly sports nutrition) is “if some is good, more must be better”. If one protein shake helps recovery, then three will make my recovery three times as good. Fluid prevents dehydration and improves performance, so let’s guzzle down as much as possible.

But as sports dietician Alan McCubbin writes, this mentality is not only ineffective, in many cases it's detrimental to your performance and even your health.

I’ve heard dozens of stories from clients and other athletes over the years, ranging from people taking triple doses of protein shakes through to one unfortunate soul who ruined his goal race by loading up on huge amounts of magnesium in the hope of preventing cramps. He certainly prevented the muscle cramps, because instead of racing his bike he spent the day sitting on the toilet.

Because when it comes to sports nutrition, it’s all about finding the sweet spot.

Hormesis – Finding the sweet spot

The term “hormesis” is used in biology to describe a relationship between the dose of something and the benefit or harm from it, in particular when too much of something is just as harmful as too little. Because of this, the optimal dose of anything that follows this relationship can be described as a “sweet spot”.

One of the most simple examples that follows this relationship is sunlight – too little exposure and you’ll be Vitamin D deficient; too much results in sunburn and eventually skin cancer.

When you look at various sports nutrition strategies, virtually everything your body extracts from food follows this relationship.

Vitamins – too much of a good thing?

Yes, you can have too many vitamins. Vitamins can be divided into fat-soluble (i.e. can be stored in fat deposits, mainly in the liver) and water-soluble (dissolvable in water with excess usually flushed down the toilet in your urine).

The earliest example of vitamin overdose (or toxicity) occurred during Antarctic exploration in the early 20th century. There were a series of unexplained illnesses and deaths from liver failure in this group. On investigation it was found that the deaths were caused by Vitamin A toxicity. This in turn was traced back to the diet of the explorers who were eating dog liver, an extremely high source of Vitamin A.

Since that time, other studies have suggested that taking high-dose vitamin and antioxidant supplements might not be a good idea. In 2012 a Cochrane Review (one of the most respected and thorough reviews of scientific studies available) was published, reviewing all studies of antioxidant supplements (beta-carotene and Vitamins A, C and E are all considered antioxidants). They concluded that there was no evidence to support the use of antioxidant supplements for the prevention of illness, and in fact “Beta-carotene and Vitamin E seem to increase mortality (i.e. death), and so may high doses of Vitamin A.” So it looks like you’re better just eating your fruit and veggies.

Even the humble Vitamin C tablet appears to be detrimental, at least to exercise performance. Several studies have now looked at Vitamin C in doses of around 500mg/day (a dose typically seen in Vitamin C tablets and some multivitamins). They have found that Vitamin C supplementation does not improve performance or adaptations to training, and in many studies it has found to be detrimental to the processes in the body that are responsible for training adaptation and performance gains over time.

What about carbs, protein, caffeine and other common nutrients that cyclists focus on?

Other nutrients also demonstrate the hormesis effect, but of course in each case the sweet spot is different. The sweet spot for carbohydrate during exercise really depends on the type of riding you’re doing, and varies from none required up to about 90 grams per hour. A lack of carbs during prolonged high intensity exercise can result in low blood glucose, which most of you have probably experienced as “bonking” or “hunger flatting” at some stage.

Excessive carbs will cause gut problems in most people, although the amount needed for this to happen varies greatly from one person to another. Extra carbs are also extra energy (kilojoules or calories) that may not be wanted depending on the situation, and for those with insulin resistance (typically described as pre-diabetes or Type 2 Diabetes) an excessive amount of carbs can cause a large rise in blood sugar, unless medication is adequate to counteract the effect.

I’ve previously written about the sweet spot for protein per meal or after exercise. It’s about 20-30g of animal based protein, and possibly more for plant-based protein sources. This dose helps to maximise the adaptations to exercise that occur in the muscles, and helps to prevent muscle loss during a period of weight loss. Excessive protein is not particularly harmful in otherwise healthy people (at least in the amounts that humans can physically eat), although it can increase the amount of calcium lost in your urine and contributes extra energy that may not be wanted. And it’s not going to help with performance.

Caffeine has a pretty well-defined sweet spot too, also described in a previous post. Around 2-3mg per kilogram of body weight seems to be optimal. Whilst you won’t have a problem with caffeine deficiency (unless you’re a regular coffee drinker who gets withdrawal), excessive caffeine doses (mostly over 10mg/kg) can cause the same problems seen with the use of stimulant drugs – anxiety, insomnia, gut problems, muscle twitching, irregular or rapid heartbeat and in extreme doses, death.

Even water follows the pattern of hormesis. Too little and your performance is compromised (if you’re sweating enough out for long enough to be an issue of course). Too much over a short period of time is fairly harmless, but over a longer period (several hours) some people fail to pee out the excess, resulting in fluid overload or hyponatraemia. My last post back in April discussed this in more detail.

I’ve finished off with a little table that summarises the “sweet spot” for each of these nutrients and supplements, as well as a few more that are relevant to cyclists. The consequences of excessive amounts vary in severity from “no performance benefit” to “risk of illness”. In some cases the dose required to reach “toxicity” is so high that it’s unlikely that you could ever achieve it from a practical standpoint.

But it’s important to understand the concept of hormesis, so we can move away from the “more is better” mentality that plagues many athletes and fuels a multi-billion-dollar sports food and supplement industry.

I would be interested on your view of Iron and it’s sweet spot? Many cyclists believe this is their legal form of doping as they consume 40-60mg before their big race giving them the “edge”, whilst they smash 1000-2000mg of VitC a day believing it gives them immunity from becoming ill.
After studying a few nutrition topics at Uni and then doing some own reading I’ve just about thrown my supplement stash in the bin, for very occasional use when i believe my diet for whatever reason is lacking in certain areas (namely Veg).

Iron tablets (such as Ferro-gradumet) are typically contain around 100mg of iron, and are designed to raise iron stores in people who are deficient. That’s around 10 times the Recommended Dietary Intake.

The gut also regulates the amount of iron that can be absorbed. When the body’s iron stores are low the gut absorbs a much greater proportion of the total iron present in foods (and the tablets if taken).

In terms of performance, there is no evidence that taking iron supplements will improve performance when iron stores are already normal, and if someone is genuinely deficient to the point of anaemia it can take weeks or even months of supplementation to return stores to normal. The AIS have been looking at intramuscular iron injections to return iron stores (and performance) to normal more quickly. Again this is in people with significant iron deficiency – there’s no evidence it will help performance in people with normal iron stores.

I’m also not aware of any other evidence or mechanism by which a one-off dose of iron could improve performance.

The issues with excessive iron consumption in someone with normal iron stores are threefold:

1) Iron competes with other nutrients for absorption, so excessive intake of iron can reduce the absorption of zinc and copper

2) Iron tablets can cause constipation in some people

3) A small number of people (estimates vary from 1-6% of the population) have a genetic condition called haemochromatosis. It can go undiagnosed for years, and for someone with this condition the use of iron supplements can result in serious health consequences. For that reason I would never recommend anyone takes an iron supplement unless they have been tested and diagnosed with a genuine iron deficiency.

rr

Antarctic explorers who were eating seal and polar bear liver.
ummmm….. no!
not if they were in the antarctic, there are no bears there.
It was in fact dog livers that did them in.
a small mistake that makes the otherwise good article miss its sweet spot.

rr

so they changed it.
now they just have the date wrong.
“The toxicity of certain foods that contain high amounts of vitamin A has
been recognized for centuries. The 1597 diary of Gerrit de Veer,”

Ian

Jeepers mate, you must be having a slow day. You’re logged into a website that, without any charge to you, offers up a lot of information, including the articles from Alan McCubbin. Chill out a bit and enjoy it. Maybe save the pedantry for the stuff you pay to access.

XoseM

edit: it reads “Artic” now

rr

yes it does, but the link is about somthing that happened in the 1597.
where as Mawson was in the early 1900s.
they could have made the change to dog livers and it would have been correct or as you say “artic” and 16th Cent.
it is just as wrong as before, but now they have fail at fixing it.

Mark

I agree “Antarctic/dog’s liver/early 1900s” is the way to go. The classic vit A overdose. The soles of their feet dropped off and Mertz bit his finger off before dying, Mawson survived. What an epic journey.

http://www.nextlevelnutrition.com.au Alan McCubbin

Yes that was my mistake, the issue with polar bear liver came from Arctic exploration and much earlier than the 20th century.

hairylegs

This is all well and good, but what is the sweet spot for pies?

http://www.nextlevelnutrition.com.au Alan McCubbin

Knowing you I’d say about 4-6. But we’ll see when we ride on Sunday ;)

RayG

After riding up Macquarie Pass to the Robertson Pie Shop? Three.

Sean

I’m not happy with this article, it’s in serious breach of all nutrition writing conventions. Mr McCubbin you have failed on so many levels, I feel obliged to point them out.

Firstly, you’ve failed to mention a single fad diet.
Second, you’ve failed to promote a miracle pill or potion.
Thirdly; you failed to demonise a food group
Nithly, you appear to have university qualifications, all university qualifications have been debunked by nutrition bloggers.
eleventy; You didn’t point out that big broccoli is taking over, they control everything we eat and are the sole reason we’re fat and turn to supplements.

Forth; You did sell me anything

Sean

‘did sell’ should read as ‘didn’t sell’

Captain Buckfast

A lot of people keep banging on about athletes being Vitamin D deficient despite spending more time outdoors than the average person. Saw the abstract of a study of footballers that showed most of the sample were Vit D deficient. Ideas?

velocite

I had a blood test the other day and my vitamin D was lower than the ‘normal range’. I ride about 10 hours per week, wear short sleeves and don’t use sun screen. I read an article on ‘The Conversation’ recently about this, and it said that the recommended ranges are problematic and that what we have is not a lot of vitamin D deficiency but a testing epidemic. My doctor agrees.

Samaway

Wow, you should probably use sunscreen ;)

Sean

Wern’t they saying not to use it in winter or something like that?

velocite

Yeah, I know, I know. But it’s yuk!

velocite

I understand and certainly I subscribe to the idea of drinking when I’m thirsty, ie I drink when my body tells me to. I don’t have a lot of sugar in my diet, off the bike that is, but sometimes, often before bed, I have a craving for something sweet, so I swallow a dessert spoon of honey. So I’m wondering this: do our cravings/desires for various sorts of foods signal something useful, or are they produced merely by a desire for gratification?

Dr Sean

You’re probably just undercarbed (bro-science terminology), eat more real carbs from whole food sources. Fruit and vegetables get almost all their calories from carbs, they’re also packed with lots of other goodies. Only about 5% of the population consume the recommended intake, a lot of us think this recommendation is on the low side anyway. Is it any wonder the population is looking for supplements, fad diets or scammer cooks with their activated woowoo and bloggers who try to pass themselves off as experts.

A little sugar won’t hurt you, just don’t overdo the added sugar.

Mark

I struggle to hit the sodium bicarbonate sweet spot. At 70 kg I should be downing 21 grams a day for optimal performance?

Adrian

I think it relates to bicarb loading protocol. Which is useful for track pursuit or short TT’s.

Dave William

That’s an interesting topic one that should be given some tought. I believe there’s no need for near as supplementation as a serious cyclist does. Just look at these colombians. They didn’t take all that stuff and still got to the top of cyclng and faster than the rest. I don’t think they used supplement just like most didn’t use powermeters or even heart rate monitors.
We think these things are essential but in some way they may be preventing us from improving.